Polymer compositions for 3-d printing and 3-d printers

Abstract

Provided are polymer compositions and methods of making 3D structures. The polymer compositions include a polymer component (e.g., siloxane polymer) having a plurality of vinyl groups and a polymer component (e.g., siloxane polymer) having a plurality of thiol groups. The polymer compositions can be used to form elastomeric 3D structures. Also provided are 3D printers having an exposure window comprising a film of an organic polymer disposed on the outer surface of the exposure window.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Application No. 62 / 369,327, filed on Aug. 1, 2016, the disclosure of which is hereby incorporated by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0002]This invention was made with government support under contract no. E55-8204 awarded by the National Aeronautics and Space Administration Jet Propulsion Laboratory. The government has certain rights in the invention.FIELD OF THE DISCLOSURE[0003]The disclosure generally relates to polymer-based 3D printing compositions and uses of such compositions. More particularly the disclosure generally relates polysiloxane-based 3D printing compositions with polysiloxanes having thiol and vinyl groups and 3D printing using such compositions.BACKGROUND OF THE DISCLOSURE[0004]Advances in material science and manufacturing technologies permit the fabrication of machines comprised entirely of soft components. Such devices deform continuously...

AI Technical Summary

Benefits of technology

This patent allows for the rapid production of detailed silicone devices through 3D printing. This process uses a liquid material that is cured by a process of light-based printing, resulting in high-quality objects with precise detail. Compared to other 3D printing methods, stereolithography is faster, has higher resolution, and can be used to produce larger objects.

Problems solved by technology

Such devices deform continuously about their surface, respond to external loads via mechanical compliance, and can perform complex functions in uncontrolled environments.

Soft machines, however, are highly constrained in their construction due to the current practical limitations of lithography and molding processes.

Shaping polymers from rigid molds is the most common method for manufacturing elastomeric devices because it is easy and compatible with a wide variety of chemistries; this strategy, however, is architecturally limited to prismatic structures restricting the design and function of soft machines.

Direct Ink Writing (DIW) enables the 3D printing of elastomeric chemistries, but the process must choose between high resolution or expedited print times; even with multiple printheads, forming large and complex geometries at high resolution requires long processing times. Further, overhanging designs require sacrificial supports, and more complex architectures are entirely un-printable.

This requirement constrains SLA chemistries to those that undergo free radical chain-growth polymerization (CGP) upon photoirradiation ultimately limiting the set of available SLA materials.

The main limitation to stereolithography is the lack of compatible materials, particularly elastomeric materials.

The viscosity requirements of the liquid pre-polymer resin during processing limit most current stereolithography resins to those comprised of monomeric and oligomeric acrylates and epoxies.

Consequently, these materials are highly crosslinked and glassy at room temperature, therefore exhibiting ultimate strains below 90% and limiting technical applications.

Traditional manufacture of soft elastomeric devices relies on soft lithography, through which only limited architectures can be obtained without labor intensive post processing steps to remove material or combine multiple layers which undermine mechanical integrity.

Of the hydrosilylation resins that can be photoinitiated, none have been utilized, to date, in stereolithography, and they suffer from long cure times incompatible with rapid prototyping or yield brittle final products.

Extrusion based systems like Structur3D and Picsima have recently developed the capabilities to fabricate 3D silicone objects, but these techniques still suffer from low resolution, long build times and other issues inherent to extrusion printing.

Although soft robotics promises a new generation of robust, versatile machines capable of complex functions and seamless integration with biology, the fabrication of such soft, three dimensional (3D) hierarchical structures remains a significant challenge.

Current SLA materials and processes are prohibitively expensive, display little elastic deformation at room temperature, or exhibit Young's moduli exceeding most natural tissues, all which limit use in soft robotics.

To date, the majority of SLA formulations are concentrated solutions of acrylate monomers and crosslinkers that rapidly reach their gel point upon photoexposure, which is necessary for printing; however, the uncontrolled propagation reaction during CGP leads to further chain-growth, ultimately yielding dense, stiff and brittle networks that display significant shrinkage and incorporate large residual stresses.

The printer required to use these proprietary materials is also prohibitively expensive for most research groups.

Additionally, the most extensible of these materials possesses poor resilience at room temperature owing to the irreversible deformation of soft-segments along their polymer backbone.

Thus, current acrylated-based SLA materials are impractical for soft machines that require high fatigue strength or cyclic loading (e.g., springs, living hinges and soft robots).

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